118,838 research outputs found
The comparative ecology of Minuartia verna (L.) Hiern and Thlaspi alpestre L. in the southern pennines, with special reference to heavy metal tolerance.
No full textMinuartia verna (L.) Hiern and Thiaspi alpestre L. are
recognized as relict elements of a preglacial montane flora in the
British Isles and, as such, display a markedly disjunct distribution
pattern. Their present-day distribution shows a close association with
metalliferous mine workings, particularly in the Pennines, where both
species have become prominent components of the flora of calcareous
lead mine wastes. By comparison with M. verna, T. alpestre is more
restricted in its distribution and is a rarer species.
The work reported in this thesis attempted to provide an
explanation for this pattern of distribution in the southern Pennines
on the basis of comparative studies of the autecology and genecology of
the species, their population biology and dynamics in the field and
their responses to competition from other species.
Both field and laboratory studies confirmed that the two
species were highly tolerant of the heavy metals lead, zinc and
cadmium. Short- and long-term solution culture experiments on tolerance and uptake of these heavy metals by a range of populations of both
species are reported. Tolerance to other toxic metals was also
investigated. T. alpestre showed superior tolerance to M. verna in
these experiments, and emerged as a metal-accumulating species. M.
verna by contrast, operated some degree of metal exclusion, but metal
uptake and distribution differed for the various metals in both species
and seasonally. Differences in metal tolerance and uptake characteristics alone could not explain the different local distribution patterns
in the field, as sites of similar metal status are colonized by both
the two species together and by M. verna alone.
A study of inter-population variation in morphological
characters showed considerable genetically-based variation in both
species. M. verna was however more variable. Some of the variation
detected was interpreted as being ecotypic in origin. The contrasting
breeding of the two species and their seed biology are considered to be
major factors in explaining the present-day distributions of the two
species. The tendency for inbreeding in T. alpestre has severely
limited its genetic variability within populations and potential for
spread. Seedling mortality of both species in their natural habitats
is very high, and survival can be related to early shelter effects of
neighbouring plants. Both species, however, emerge as weak competitors
as predicted from their preference for open habitats with much more
bare ground.
The relevance of these studies to the interpretation of the
present-day global distribution of the two species and their evolutionary biology is discussed
Interview with Verna L. Reichert, 1986
No full textVerna Reichert, born and lived in La Grange her entire life, and friends Murlene and Atlan Citzler, talk about their experiences during the early 20th century. Also includes a La Grange publication, The Hanging Tree, which relates two criminal cases and Sheriffs of Fayette County who were involved
Integration between oncology and palliative care: does one size fit all?
No full textReply to the letter to the editor 'Integration between oncology and palliative care: does one size fit all?' by Verna et al
Verna Reese
No full textVernetta "Verna" Reese is pictured her eighth grade at Uintah High School. She was born to Jacob Burton and Esther Reese on June 24, 1927. She married Author L. Holt. She worked for and retired Boeing Aircraft for thirty years. She died December 7, 2009
Draba verna L. (Brassicaceae/Cruciferae): A salt averse taxon
No full text-In this study, it was aimed to determine whether Draba verna L. (=Erophila verna (L.) Chevall. subsp. verna (L.) DC.), which is a relative of model organism Arabidopsis thaliana (L.) Heynh. and distributing around saline areas, is a halophyte or not and to research the salinity tolerance during germination period. D. verna seeds were germinated at distilled water and different NaCl concentrations (100, 200, 300, 400, 500, 600, 700, 800, 900, 1000 mM) at 8ºC/16ºC 12/12 h photoperiodism (light intensity 12000 lux ±%10) for 20 days. The NaCl concentrations and the germination percentages were as follows distilled water 100%, 100 mM NaCl 83%, 200 mM NaCl 2%, 300 mM NaCl 1% and no germination over 300 mM NaCl. Un-germinated seeds were taken into recovery and show 87.3% mean germination, and the ones still ungerminated were tested for viability. Increase in salinity, cause decrease in germination rate which means that D. verna is not resistant to salinity but salinity has important pressure on germination. The tolerance of D. verna seeds to salinity, although it has a wide distribution area at saline areas, is result of decrease in soil salinity during germination period. It can be concluded that D. verna is not a halophyte it is a salt avoider
Draba verna L.
No full textV. verna L. Cat. 273. Verbreitet in dem vom Cat. umschriebenen Gebiet (Trient-Münster); ausserdem: Simplonsüdseite (Becherer). Bis 2720 m: Südseite des Gornergrates bei Zermatt, westlich der Felsecke von Gadmen (Zoller 1951); ein anderer hoher Fundort, ebenfalls bei Zermatt, ist: bei den Hütten der Fluhalp, 2610 m, Dungstelle, ein Exemplar (Becherer 1950).Published as part of Becherer, 1956, Florae Vallesiacae Supplementum, pp. 1-556 in Denkschriften der Schweizerischen Naturforschenden Gesellschaft 71 on pages 1-55
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